There's quite a few guys who've done this with build threads on 'aussiev8'. A couple quite neat, a couple pretty rough! (couple of good discussions on sump options too). Also take a look at an American site like 'ls1tech' for shift position discussions in things like 67-9 Camaro

As Adam mentioned, the main issue seems to be how far back the Commodore shifter is - so not just tunnel mods/changes but guys are cutting further back too. The Mal Wood extention housing ($$) is said to bring the shifter out in the standard position , but the one car I've seen with one still had maybe a little under half an inch out of the raised 'box' section (sorry dont know how to describe it) where the tunnel ends and the flat floor starts.